My (new to me) property has a TT supply with a 30mA RCD protecting all the MCBs (not ideal but not causing inconvenience so far). There is a substantial Earthing Rod robustly connected to the earth bar of a modern Consumer Unit. PME is not available so far as I am aware.
The RCD trips via its Test button or if I simulate a 30mA leak from Live to Earth. However, if I short Neutral to Earth at a ring main socket the RCD does NOT trip, which I understand to be incorrect (and certainly not as per my previous property).
If I measure the current which flows from N to E it's about 18mA (not enough to trip) and this reduces (!) to about 16mA if I increase the house load e.g. by turning on a cooker. There is a constant approx. 5 volts ac between Neutral and Earth. I have tried measuring the earth rod resistance by installing a second earth rod some distance away but bizarrely even with the RCD off (so no house load) there is about 5 volts ac between this new rod and the old one which messes up any attempt to measure resistance with a multi-meter.
I'm guessing that my earth rod has a problem but is it also possible that the neutral from the supply company has a poor earth? I live in a very rural area. Any suggestions much appreciated before I call in a professional with the right test gear.
The RCD trips via its Test button or if I simulate a 30mA leak from Live to Earth. However, if I short Neutral to Earth at a ring main socket the RCD does NOT trip, which I understand to be incorrect (and certainly not as per my previous property).
If I measure the current which flows from N to E it's about 18mA (not enough to trip) and this reduces (!) to about 16mA if I increase the house load e.g. by turning on a cooker. There is a constant approx. 5 volts ac between Neutral and Earth. I have tried measuring the earth rod resistance by installing a second earth rod some distance away but bizarrely even with the RCD off (so no house load) there is about 5 volts ac between this new rod and the old one which messes up any attempt to measure resistance with a multi-meter.
I'm guessing that my earth rod has a problem but is it also possible that the neutral from the supply company has a poor earth? I live in a very rural area. Any suggestions much appreciated before I call in a professional with the right test gear.